Pity the poor moviegoer who watches the commercials for "Good Luck Chuck," mistakes it for a light romantic comedy, and takes his prudish grandmother to the theater. There are at least two dozen graphic, profanity-filled and occasionally violent sex scenes in the film. The picture ends with Dane Cook thinking up different ways to pleasure a stuffed penguin.

That closing-credits sequence is by far the funniest thing in the disappointing movie, which wastes the talents of Cook and overestimates the limited abilities of co-star Jessica Alba. Even worse, the movie tries to be "When Harry Met Sally" and "Debbie Does Dallas" at the same time, mixing serious relationship scenes with impressive levels of raunch, nudity and creative sexual positioning. The resulting tone is so off-kilter that both themes fail.

Cook plays a nice-guy dentist named Chuck, and that's the first casting mistake. Like Robin Williams and Lewis Black before him, the stand-up comic always seems to be teetering on the edge of insanity. Giving Cook conventional story lines and long romantic speeches is like watching a grizzly bear in a tutu riding a unicycle. You might actually start rooting for the comedian to completely lose it, walk behind the camera and maul the director.

Chuck is cursed during a boyhood game of spin the bottle, so that every woman he sleeps with as an adult follows the tryst by finding her true love. The constant sexual advances are a blessing at first, until Chuck falls for penguin trainer Cam (Alba) and realizes they can't be together. With nowhere to go from there, the scriptwriters struggle to wrap up the movie, mixing "Three's Company"-style misunderstandings, "Deuce Bigalow"-style sexism and borrowed ideas from at least three episodes of "Friends." (Chuck doesn't end up on a plane to Yemen, but he does pay $17,000 for a last-minute flight to Antarctica.)

Alba is so exceptionally challenged as an actress, it almost seems politically incorrect to make fun of her. Good writers and directors know her shortcomings and find ways to limit her thespian workload, allowing her to frolic repeatedly underwater ("Into the Blue"), dance in a strip club with a lasso ("Sin City") or periodically turn invisible ("Fantastic Four"). In "Good Luck Chuck," Alba must not only emote, but also pull off clumsy-girl slapstick scenes, which she can't. Cook and Alba are among the best in their respective fields - stand-up comedy and looking hot - yet they're both almost completely wasted here.

Thankfully, no one tries to restrain fellow comic Dan Fogler, who plays Stu, Chuck's foulmouthed and weak-moraled plastic surgeon buddy. Fogler and "30 Rock" regular Lonny Ross as Cam's stoner brother pretty much carry the movie - at least until the end, when a Chuck-as-stalker story line develops and Cook is finally allowed to cut loose a little bit.

It's worth mentioning for the third time that this movie is much closer to "Caligula" than "Sleepless in Seattle." Before you go to "Good Luck Chuck" on a first date, consider that the credits include characters called Dirty Talker, Contortionist Lover, Kitchen Counter Lover and McTitty. (No, we didn't make up the last one.)

-- Advisory: This film contains nudity, sex scenes, onscreen defecation, drug use and violence. And that's just from the penguins.